Jet-type drilling jar



' FIG.

W. S. CRAKE JET-TYPE DRILLING JAR Filed Dec. 28, 1948 lnvenior':

Wilfred 5. (Drake His AHorney April 21, 1953 FIG. l

mmnlm IU r rainy/wf] 2 w M m w M ,L n w w w M y@ w v Patented Apr. 2l, A1951? JET-TYPE DRILLING JAR Wilfred S. Crake, Houston, Tex., assignor to Shell Development Company, San Francisco, Calif., a. corporation of Delaware Application December 28, 1948, Serial No. 67,708

4 Claims.

This invention relates to a well tool and pertains more particularly to a. jarring tool which may be lowered on a cable through a drill string for applying a jarring force to said drill string.

In drilling an oil well, it occasionally happens that the tubing or drill string becomes jammed in the well borehole by cavings of sand, formation debris or rock fragments falling into the borehole andwedging the drill string and drill bit attached thereto. The wedging materials around the bit or drill string are frequently compacted to such extent that circulation of drilling fluid cannot be relied upon to wash them away and release the bit. Accordingly, the bit or drill string can only be freed by applying a severe jarring action to the stuck member.

A tool commonly used is a mechanical jar adapted to be attached to the lower end of a drill string and run into the well, where it is connected to that portion of the drill string that is lodged in the well borehole. The mechanical jar permits a reciprocating or limited vertical movement of the upper part of the drill string, said reciprocating movement causing jarring action to the stuck portion of the drill string. The main disadvantage with this type of jar is that the drill string must be withdrawn from the well, equipped with the jar, and then reinserted into the well to be connected to the stuck section of drill string in the well.

The primary object of the present invention is to provide a jarring tool adapted to be lowered on a cable within a drill string and positioned in a stuck section of said drill string for engage ment therewith.

Another object of this invention is to provide a cable jarring tool adapted to eiect a jarring and strong uplifting action at the point. or close to the point, at which the drill string is stuck or wedged. j

A further object of this invention is to provide a cable jarring tool adapted to impart a jetting effect to a well fluid within the drill string to aid or restore circulation within the well whereby said `fluid. may dislodge and wash away any materials that tend to immobilize the drill string.

Another object of this invention is to provide a jarring tool of simple and sturdy construction that is readily insertable into and removable from a drill string without the removal of any portion of said drill string.

Other objects and advantages of the present invention will become apparent from the following description, taken with reference to the drawing, wherein:

Figure 1 is a longitudinal View, partly in cross section, of the present jarring tool positioned within a rotary drill string.

Figure 2 is another view in cross section of the jarring tool of Figure l, after an explosive charge carried by said tool has been detonated.

Figure 3 is a cross-sectional view of the present jarring tool incorporating a gas expansible anchoring means.

Referring to Figure 1,'the present jet-type drilling jar I0 is shown in place inside a heavy drill collar I4 at the bottom of a drill string. In this case, cavings 20 have wedged the drill bit I5, carried at the lower end of the drill string, against the wall I9 of the well borehole. One or more apertures I6 in the drill bit form huid outlet means whereby a drilling iiuid may be circulated during drilling operations by pumping ,it down through the drill string I4, out the apertures I6 and upwards in the annular space I8 between the outer wall of said drill string and the wall I9 of the borehole.

The present jar I0 may be run into the well o a cable II, preferably containing an insulated electrical conductor 38 for iiring an explosive. It is to be understood that an ordinary cable or wire line may be used if mechanical devices are employed to ignite the explosive. In this embodiment the cable II is attached to a cable socket 39 and the electrical conductor 38 is run through or alongside a sinker bar I2 and a hammer-andanvil type mechanical jar that may be interposed between the cable I I and the tool I Il to aid in sinking the tool I0 in the well and in jarring it free from the surrounding drill string or collar I4. The electrical conductor 38 continues: downward through the tool I I) .terminating at a chamber 33 adapted to contain a detonating mechanism.

The jet-type jar I0 comprises a cylindrical body member 2l, a portion 22 thereof having a reduced diameter. Carried on or integrally formed with said body member 2I is a slip bowl or multiple slip bowls 23 having outer tapered faces. Slidably mounted for limited longitudinal movement on said body 2| is a jar anchoring means which comprises a ring or sleeve 24 to which is attached, in any suitable manner, e. g. welding a plurality of vertically depending slip arms 25 which may be either hinged or made of a flexible material whereby they may be spread outwardly toward the inner Wall of said drill string I4. The lower ends of the slip arms 25 are provided with gripping elements or slips 26 having toothed or serrated faces that are curved to conform to the inner surface of the drill string I4. The slips 26 are mounted in slidable engagement with the slip bowls 23, being normally held in their retracted position, as shown in Figure l, by a tension spring 21. Pins 2B or other suitable fastening means secure the top of the spring 2`I to the body member 2 I.

Removably affixed to the bottom of the body member 2l, in any suitable manner, as by screw threads 37, is a thick-walled cylinder 29 having a central chamber 33 formed therein, which chamber contains suitable firing mechanism for igniting an explosive charge. A thick-walled housing 39, having an axial bore 3| therethrough, is secured by screw threads 32Y to the lower end of cylinder 23. The axial bore 3l of said housing 33 forms a chamber in which a charge of explosive 34 may be carried. Chamber 33 con'- taining an explosive cap or a ring mechanism (not shown) and chamber 3l housing the explosive charge 34 are interconnected by a suitable passageway 35, The lower end of the axial bore 3I maybe tapered as' at 33, if desired, to concentrate and focus the blast from the charge 34a/hen saidoharge is detonated,

Any suitable amount and type of explosive charge 3d may be used depending on the amount of jarring and lifting action desired. Preferably the explosive is a slow-burning type smokeless powder of the type used as a propellant charge for military purposes. It is desirable to use a Waterproof type explosive as the borehole of the Well is generally lled with fluid. Alternatively, an explosive charge .covered with a waterproof material or carried in a waterproof container may be employed, said material or container being of an easily destructible and relatively thin material such as, for example, rubber, plastic, parchment, aluminum or other metallic foil, and the like.

When the present jarring tool is employed to jar free a drill string I4 with drill bit 15,. the point at which the drill string is stuck is previously determined by suitable means well known to the art, such as a magnetic tester. vThe jarring tool IJ is then attached to the end of the cable' II and lowered through the drill string VI4 to the level at which the drill pipe is stuck. In this case, the cavings 23 are illustrated as .Wedging the drill .bit I in place against the Wall of the Well I9. Hence, the jarring tool IU is lowered to a position just above the drill bit I5. In. operation, the electrical conductor cable Il may be attached to a suitable power source and switch means (not shown) at the surface. With the explosive carrying jarring tool i0 in place, as shown in Figure l., the firing mechanism orcap contained in. chamber 33 is actuated orflred to ignite the explosive jet charge 34. The gases generated by the igniting charge 34 discharge downwardly through the axial bore causing the parts of the tool body 2l, 22, 23 and30 to move vertically upward.

The inertia of the spring-supported slip assembly, oomprising ring 24, arms 25 and slips 26, causes it to stand momentarily substantially still whereby the spring 2l is extended and the .slips 25 are caused to move outwardly as the backs of the slips slide over the faces of the rising slip bowls 23. The slips move outwardly until the teeth of the slips 26 engage the inside of the drill string Ifl, as shown in Figure 2. Thus, the upward vertical movement of the tool body 2l, 22, 29 and 3l! is arrested and the remainder of the explosive thrust is transferred to the drill string I4 whereby said drill string is subjected to a sharp jarring and uplifting action. Prior to firing the explosive 34, the drill string is preferably subjected to a strong upward pull from the surface so that considerable tension exists in the drill string. The vertically-directed explosive rea-ction of the jet adds greatly and suddenly to this tension, helping to jar the stuck drill pipe free and causing the cavings 29 to be crushed or jammed into the borehole wall I9.

.After the explosive force is spent, the weight of the tool body 2|, 22, 29 and 30 is normally suflicent to disengage the slips 26 from the inner Surface-of the drill string I4 as the drilling jar is allowed to drop slightly. If this fails to disengage the slips 26, a mechanical jar I3 may be actuated by pull or release of the cable I I. Either action causes the'slip` bowl 23 to slide downwardly from the position shown in Figure 2 to that shown in Figure l, whereby the slips 26 are disengaged. The spring, 2l pulls theV ring 24 andattached slip arms Y25 and slips 2S into their retracted. position (Figure l) thus allowing the jarring tool IIJ- to. be withdrawnto the surface by the cable II.

An additional advantage of the present jarring toolV is that the explosive discharge jetting-action may be utilized to restore circulation in a well borehole. It occasionally happens that circulation of drilling fluid down the pipe string Ill-,out the apertures IB of the bit I5. and into the annulus ITS, is blocked byV cavings 20 in the-annulus I8 rabove the drill bit. .At such. times, the pressure capacity of the mud pumps at the.. surface is usually not sufficient to cause the pumpedfluid to washthese .cavings 2l)4 away and restore circu: lation. By using the.v present jet jarring toolv and firing it immediatelyabove thedrll bit I5, a very high pressure is created inside the lower endof thedrill string I4 which is sufficient. to dislodge the cavings 2li and restore circulation in the Well.

Another embodiment of thepresent jarring device is shown in Figure 3 whereina portion of the gases, generated during the explosion,` is utilized to expand the anchoring means carried. by said device. Aixed to a sinker bar I-2 which is. in turn secured. to the lower end .of a cable.V II containing an electrical conductor, is a body member 5U' having a recessedwall portion 5l adapted t0 house a plurality of anchoring slips 52. A plurality of lateral piston chambers 53 areformed in said recessed wall portion, said chambers being in communication with an axial bore 54m. said body member 59 which also serves as a. chamber for housing detonating means or materials.v

Slidingly mounted for lateral movement in the piston chambers 53 in a substantially fluidtight manner are a plurality of pistons 55 thatare iixedly secured to the inner surfaces of the anchoring slips 52. Theslips 52 are-curved to conform with the inner surface of a surrounding drill string 56. The faces of the slips 52.are serrated or toothed for gripping the .inner surface of the drill string 56 when expanded thereagainst. The electrical conductor El carried by the cable I I extends through the sinker bar I2 and into the chamber 54 housing the ignition means (not shown).

Threadedly secured to the lower end ofthe body member 53 is a housing member having an axial bore. therethrough. The upper part 58 of the bore is enlarged to form. a chamber for containing an explosive charge 59 while the lower portion 60 of said bore is shaped to direct the explosive blast downwardly.

In operation, the present jarring. tool is lowered into a drill string 56 to a predetermined depth where the charge 59 is exploded in a manner previously described. A portion of the `gases generated during the explosion is forced into the axial bore 54 of the body member 50. The pistons 55, in communication with said axial bore 54, are instantaneously forced outwardly by the gaseous pressure causing the attached slips 52 to contact the inner wall of the drill string 56, thus iixedly anchoring the tool in place during the time period required by the explosive bases to escape through the bore 50. It will thus be seen that upon the iiring of the explosive charge the drill string 55 is subjected to a sharp jarring and strong uplifting action in a manner similar to that described with regard to the apparatus of Figures 1 and 2.

I claim as my invention:

1. A jarring tool adapted to be lowered on a cable within a tubular string in a well, said tool comprising an elongated body member, a chamber in said body containing an. explosive charge, means in communication with said chamber for exploding said charge, a downwardly extending passageway opening to the space below said tool to conduct the explosive gases escaping therefrom, radially expansible anchoring means slidably secured to said body member for longitudinal movement thereon, and wedge-shaped cam means carried on the body member for causing the anchoring means to expand radially.

2. A jarring tool adapted to be lowered on a cable within a tubular string in a well, said tool comprising an elongated body member, a chamber in said body containing an explosive charge, means in communication with said chamber for exploding said charge, a downwardly extending passageway opening to the space below said tool to conduct the explosive gases escaping therefrom, whereby an upward reaction thrust is developed to move said body member upwards, radially expansible anchoring means slidably secured to said body member for longitudinal movement thereon, and wedge-shaped cam means carried on the body member for causing the anchoring means to expand radially.

3. A jarring tool adapted to be lowered on a cable within a tubular string in a well, said tool comprising an elongated body member, a chamber in said body containing an explosive charge,

means in communication with said chamber for exploding said charge, a downwardly extending passageway opening to the space below said body member to conduct the explosive gases escaping therefrom, whereby an upward reaction thrust is developed to move said body member upwards, anchoring means outwardly carried by said body member, said anchoring means comprising a slip bowl having a tapered outer face fixedly carried on said body member, ring means slidingly surrounding said body member, a plurality of slips depending from said ring means and spring means affixed to said body member and said ring means for resiliently supporting the slips in a normally inoperative retracted position in sliding contact with the slip bowl.

4. A jarring tool adapted to be lowered on a cable within a tubular string in a well, said tool comprising an elongated body member, electrical cable means for lowering said tool in the well and conducting current thereto, a chamber in said body containing an explosive charge, detonating means carried by said body member electrically connected to said electrical cable means and in communication with said chamber for exploding said charge, a downwardly extending passageway opening to the space below said body member to conduct the explosive gases escaping therefrom, whereby an upward reaction thrust is developed to move said body member upwards, radially expansible anchoring means slidably secured to said body member for longitudinal movement thereon, and wedge-shaped cam means carried on the body member for causing the anchoring means to expand radially.

WILFRED S. CRAKE.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,065,135 Huddleston et al. Dec. 22, 1936 2,076,307 Wells et al Apr. 6, 1937 2,250,574 Dodge July 29, 1941 2,266,382 Quintrell et al Dec. 16, 1941 2,300,438 Spang Nov. 3, 1942 2,330,265 Burt Sept. 28, 1943 FOREIGN PATENTS Number Country Date 52,014 France 1861 

